Hi Guys I am novice to motor control. I used L2 93 to drive 2 RC motors. Then it just burned out. I don't understand why this happened and how to fix the problem.Do you guys have any ideads to test it?

Do you have any more information about the 2 RC motors you used? It is very possible that you asked the L293D to provide more power then it was designed for. The L293D can provide 600 mA and up to 1.2 A peak. If you exceed that things don't go well.

To measure stall current of a motor, get out ye trusty multimeter and set it to measure current.hook it up accordingly for measuring current(as if in series) with the battery in like normal, hold the shaft still and see what the current draw is, this is your stall current, this is the max current your motor will draw.so it will be:(battery+)-(multimeter probe) (multimeter probe)-(motor) (motor)-(battery -)

The L293D drawing 12 mA is just how much current the chip itself uses to control the motors, how much IT uses.You may have a short somewhere, but my money is on the motor drawing too much current.You can probe around a bit in your circuit and look for some shorts if you want.